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Subject[PATCH] ima: drop vla in ima_audit_measurement()
Date
In keeping with the directive to get rid of VLAs [1], let's drop the VLA
from ima_audit_measurement(). We need to adjust the return type of
ima_audit_measurement, because now this function can fail if an allocation
fails.

[1]: https://lkml.org/lkml/2018/3/7/621

Signed-off-by: Tycho Andersen <tycho@tycho.ws>
---
security/integrity/ima/ima.h | 4 ++--
security/integrity/ima/ima_api.c | 31 +++++++++++++++++++++++--------
security/integrity/ima/ima_main.c | 7 +++++--
3 files changed, 30 insertions(+), 12 deletions(-)

diff --git a/security/integrity/ima/ima.h b/security/integrity/ima/ima.h
index d52b487ad259..8e2470f72f7f 100644
--- a/security/integrity/ima/ima.h
+++ b/security/integrity/ima/ima.h
@@ -201,8 +201,8 @@ void ima_store_measurement(struct integrity_iint_cache *iint, struct file *file,
const unsigned char *filename,
struct evm_ima_xattr_data *xattr_value,
int xattr_len, int pcr);
-void ima_audit_measurement(struct integrity_iint_cache *iint,
- const unsigned char *filename);
+int ima_audit_measurement(struct integrity_iint_cache *iint,
+ const unsigned char *filename);
int ima_alloc_init_template(struct ima_event_data *event_data,
struct ima_template_entry **entry);
int ima_store_template(struct ima_template_entry *entry, int violation,
diff --git a/security/integrity/ima/ima_api.c b/security/integrity/ima/ima_api.c
index 08fe405338e1..008d3887ae00 100644
--- a/security/integrity/ima/ima_api.c
+++ b/security/integrity/ima/ima_api.c
@@ -304,17 +304,28 @@ void ima_store_measurement(struct integrity_iint_cache *iint,
ima_free_template_entry(entry);
}

-void ima_audit_measurement(struct integrity_iint_cache *iint,
- const unsigned char *filename)
+int ima_audit_measurement(struct integrity_iint_cache *iint,
+ const unsigned char *filename)
{
struct audit_buffer *ab;
- char hash[(iint->ima_hash->length * 2) + 1];
+ char *hash, *algo_hash;
const char *algo_name = hash_algo_name[iint->ima_hash->algo];
- char algo_hash[sizeof(hash) + strlen(algo_name) + 2];
- int i;
+ int i, hash_len, algo_hash_len;

if (iint->flags & IMA_AUDITED)
- return;
+ return 0;
+
+ hash_len = (iint->ima_hash->length * 2) + 1;
+ hash = kzalloc(hash_len, GFP_KERNEL);
+ if (!hash)
+ return -ENOMEM;
+
+ algo_hash_len = hash_len + strlen(algo_name) + 2;
+ algo_hash = kzalloc(algo_hash_len, GFP_KERNEL);
+ if (!algo_hash) {
+ kfree(hash);
+ return -ENOMEM;
+ }

for (i = 0; i < iint->ima_hash->length; i++)
hex_byte_pack(hash + (i * 2), iint->ima_hash->digest[i]);
@@ -323,18 +334,22 @@ void ima_audit_measurement(struct integrity_iint_cache *iint,
ab = audit_log_start(current->audit_context, GFP_KERNEL,
AUDIT_INTEGRITY_RULE);
if (!ab)
- return;
+ goto out;

audit_log_format(ab, "file=");
audit_log_untrustedstring(ab, filename);
audit_log_format(ab, " hash=");
- snprintf(algo_hash, sizeof(algo_hash), "%s:%s", algo_name, hash);
+ snprintf(algo_hash, algo_hash_len, "%s:%s", algo_name, hash);
audit_log_untrustedstring(ab, algo_hash);

audit_log_task_info(ab, current);
audit_log_end(ab);

iint->flags |= IMA_AUDITED;
+out:
+ kfree(hash);
+ kfree(algo_hash);
+ return 0;
}

/*
diff --git a/security/integrity/ima/ima_main.c b/security/integrity/ima/ima_main.c
index 2cfb0c714967..356faae6f09c 100644
--- a/security/integrity/ima/ima_main.c
+++ b/security/integrity/ima/ima_main.c
@@ -288,8 +288,11 @@ static int process_measurement(struct file *file, char *buf, loff_t size,
xattr_value, xattr_len, opened);
inode_unlock(inode);
}
- if (action & IMA_AUDIT)
- ima_audit_measurement(iint, pathname);
+ if (action & IMA_AUDIT) {
+ rc = ima_audit_measurement(iint, pathname);
+ if (rc < 0)
+ goto out_locked;
+ }

if ((file->f_flags & O_DIRECT) && (iint->flags & IMA_PERMIT_DIRECTIO))
rc = 0;
--
2.14.1
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